Could anyone tell me if the "BSD Protection License" can be used
for main?

You should include the text of a licence when asking -legal. I think
that isn't necessary until they fix it. It does not appear possible to
meet 3c and 4c simultaneously and there is no real indication that you
mustn't meet both. Therefore, I suggest that the licence is not free.

Given the preamble, I think I can see what they are trying to do (be
incompatible with all other strong copyleft licences and let all
derivative works be possible to take proprietary), but it's botched
wording. The loose wording in the preamble further suggests that to be
the case. Remember, GPL can be used commercially too.

This touches on a frequently-asked case. It appears to offer the same
freedoms to all users, but another option to a subset.